You could write the perfect cold email and watch it die in a spam folder.
Nope, I’m not exaggerating or trying to create shock value. If inbox providers don’t trust your sender reputation, even your best message won’t make it past their filters. And email warmup is a way to build and maintain that trust.
As someone who’s helped thousands of businesses escape the spam box over the past decade, I’ve seen this happen countless times. Hence, in this read, I’ll help you explore:
- What email warmup really means
- How the warmup process works, step by step
- The mistakes that destroy your sender reputation
- Methods to track your progress and measure success
- Why warmup determines whether you reach inboxes or get blocked
Now, you could try figuring all this out yourself — or, if you’re a business, just schedule a free call with a deliverability consultant and let an expert from Maxify take care of it.
Our Maxify Inbox offers:
- Unlimited deliverability consultations
- Unlimited email warmup
- Dedicated IP address
- Email validation
We can set everything up for you right away. Want to know how?
Schedule your consultation call
What exactly is email warmup?
When you start sending emails from a brand-new address or unused domain, inbox providers see you as a stranger. And strangers often get sent to spam.
Email warmup is the gradual process of building trust with email service providers like Gmail and Outlook. You start by sending small volumes of email and slowly increase over time.
Here’s what the process looks like:
- Send a small number of emails each day to start
- Slowly increase your sending volume over weeks
- Maintain consistent behavior to prove you’re legitimate
- Get real engagement through opens, replies, and positive actions
Think of it like warming up before exercise. If you blast out 500 cold emails on day one with a new domain, you risk getting blacklisted immediately. Warmup prevents this by establishing your reputation gradually.
Why can’t you skip email warmup?
Your biggest enemy in cold outreach is not a weak subject line. It’s a damaged sender reputation. Even perfectly crafted campaigns fail when inbox providers flag your emails as suspicious.
ESPs don’t trust new senders
Email service providers use complex systems to identify spam. New domains and inactive accounts automatically raise red flags, not because of your content, but because you have no sending history.
It works like building credit (no track record means no trust).
You have to earn inbox placement
Email warmup gradually builds a sender history that tells providers you’re safe and people want your emails. Proper warmup gives you:
- Better inbox placement instead of spam folder delivery
- Higher open and reply rates because you reach real people
- Stronger domain reputation for all future campaigns
Studies show email warmup can boost deliverability by 20-35% within weeks, especially for new senders.
Even experienced senders need a warmup
You should warm up your email if you’re:
- Restarting after a long break
- Adding new domains or subdomains
- Switching email platforms or providers
- Seeing sudden drops in engagement rates
Skipping warmup is like driving without insurance (everything’s fine until it isn’t).
How does the email warmup process actually work?
Warming up goes beyond sending test emails to friends. It’s a structured process that builds credibility with inbox providers through specific phases.
Start small and scale gradually
On day one, you might send just 5-10 emails. By day 30, that could grow to 100 or more. The key is increasing volume gradually to mimic natural human behavior, not automated mass sending.
This steady pace signals to email providers that your activity is genuine.
Engagement drives everything
Sending emails is only half the battle. What matters is what happens next.
Email providers love to see:
- Emails that get opened
- Messages marked as important
- Emails moved out of spam folders
- Replies that create conversation threads
This activity builds what we call “sender trust.”
Modern tools simulate real conversations
Advanced tools like Email Warmup automate this process by:
- Sending and replying between verified inboxes
- Moving your emails out of spam and marking them safe
- Maintaining high reply rates to mimic natural interaction
Moreover, if you’re using a brand-new domain, wait at least 7 days before starting warmup (this creates a more natural sending history).
How long should you warm up?
Minimum should be 2-4 weeks, and ideal should be between 6-8 weeks. However, if you’re running cold email campaigns, you should keep them running in the background as an ongoing process.
Should you warm up manually or use tools?
Manual warmup might seem simple until you try to scale it.
If you’re only sending 10 emails daily, manual warmup could work. But managing multiple inboxes, new domains, or high volumes quickly becomes impossible.
Here’s how both approaches compare:
| Feature | Manual warmup | Tool-based warmup |
| Effort required | High (daily manual work) | Low (fully automated) |
| Scalability | Limited to 1-2 inboxes | Unlimited inboxes |
| Engagement simulation | Needs real people to reply | Auto-replies and interactions |
| Deliverability tracking | Hard to measure | Real-time insights |
| Risk of errors | High (missed replies, irregular sending) | Low (consistent patterns) |
| Duration management | Manual tracking required | Auto-managed schedules |
| Best for | Low-volume, one-time senders | Agencies, marketers, and regular cold emailers |
Tools like Email Warmup offer low-effort, scalable inbox warming for cold emailers and agencies.
Why tools win in the long term
Manual warmup is like washing clothes by hand. It’s possible, but not efficient.
Tools ensure:
- Constant interaction with clean inboxes
- Consistent sending patterns that providers trust
- Accurate tracking of spam scores and deliverability
- Time savings that let you focus on your actual business
When your time is valuable, automation becomes a must-have, not an optional choice.
That’s why most teams now use platforms like Maxify Inbox to automate their warmup, validation, and deliverability setup in one place.
What are the best practices for email warmup?
One mistake can damage your domain’s reputation for months. So you see, warmup isn’t just sending emails randomly.
Set up email authentication first
Before sending any messages, configure these DNS records:
| Protocol | Stands For | Purpose |
| SPF | Sender Policy Framework | Authorizes specific servers to send email on behalf of your domain |
| DKIM | DomainKeys Identified Mail | Adds a digital signature to ensure the email hasn’t been tampered with |
| DMARC | Domain-based Message Authentication, Reporting & Conformance | Instructs email providers how to handle messages that fail SPF or DKIM checks |
Without these, your emails look suspicious before they even leave your server.
Increase the sending volume gradually
Start small with 10-20 emails per day and increase slowly. A typical schedule looks like:
| Week | Daily Sending Volume | Goal |
| Week 1 | 10–20 emails/day | Establish basic sender trust |
| Week 2 | 30–50 emails/day | Build consistent engagement |
| Week 3+ | 75–100 emails/day | Scale outreach safely |
Ramping up too quickly triggers spam filters immediately.
Create real engagement
Warmup works both ways. Here’s how to generate the activity that email providers love:
- Encourage people to reply to your emails
- Keep conversations going by responding to replies
- Ask recipients to mark emails as important
- Use warmup tools to automatically move messages out of spam
Avoid spam trigger words
Words like “FREE,” “guaranteed,” “limited time,” and “buy now” set off spam filters. Even during warmup, write like a real person having a conversation, not like a late-night TV commercial.
You can use an email spam checker to preview your content for risky language before sending.
Keep your email list clean
Bad email addresses create hard bounces, which damage your reputation instantly. Always:
- Validate your email list before sending
- Remove inactive or unengaged addresses regularly
- Never use purchased or scraped lists (they’re full of spam traps)
Use an email validation API to detect hard bounces and fake addresses in real time.
Include unsubscribe links
If someone marks you as spam instead of unsubscribing, it hurts your sender score. An unsubscribe link gives people a clean way out without damaging your reputation.
Use email filters
Warmup generates lots of automated replies. Set up filters to organize these messages using terms like “Sent from Warmup Email Platform.” This keeps your inbox manageable.
How do you know if your warmup is working?
Email warmup isn’t something you set and forget. Without tracking results, you’re guessing whether your efforts are working or failing silently.
| Metric | What It Measures | Target | Warning/Action |
| Inbox Placement Rate | % of emails that land in the primary inbox (vs spam or promo) | 90% or higher | Below 80% = Check your setup |
| Spam Complaint Rate | High = You’re sending too fast, or the content sounds spammy | Less than 0.1% | High = You’re sending too fast, or content sounds spammy |
| Bounce Rate | % of emails that fail to deliver (esp. hard bounces) | Less than 2% | High = Clean your list and verify contacts |
| Open Rate | % of recipients who open your email | 30–50% | Low = Subject line or sender reputation issues |
| Reply Rate | % of recipients who respond | 8–10% during warmup | Focus on this more than opens (it signals real engagement) |
Run a quick email deliverability test to check inbox placement and domain trust.
Use tools that provide detailed reports
If your warmup tool doesn’t show:
- Domain reputation scores
- Deliverability trends over time
- Inbox versus spam breakdowns
You’re missing critical information. Choose tools that help you spot problems before they become disasters.
Ready to start landing in inboxes?
If your emails aren’t being seen, they aren’t being opened. And if they’re not being opened, they’re definitely not converting.
Inbox visibility is where the battle is won or lost, and Maxify Inbox is your weapon in that fight.
Whether you’re scaling cold outreach, reviving an old list, or launching a new domain, you need a warmup strategy that doesn’t just deliver emails but builds trust with inbox providers.
Here’s what effective Maxify Inbox delivers:
- Dedicated IP addresses that protect your reputation
- Expert guidance with unlimited deliverability consultations
- Unlimited email warmup that adapts to your sending patterns
- High sender scores through real-time deliverability monitoring
- Clean lists through monthly email validation and replacements
Stop watching your best emails disappear into spam folders with Maxify Inbox.
Frequently asked questions about email warmup
Here are some commonly asked questions about this topic:
What is email warmup?
Email warmup is the process of gradually increasing your email sending volume to build trust with email service providers.
By creating natural engagement patterns, such as conversations and replies, you enhance your domain’s reputation and boost inbox placement rates.
What is IP warming?
IP warming is similar to email warmup but focuses on building trust for a new dedicated IP address.
You gradually increase sending volume over time, so the IP develops a positive reputation with inbox providers.
Most cold emailers use shared IP addresses, but high-volume senders often require dedicated IP warming.
What does an email spam checker do?
An email spam checker analyzes your emails for elements that might trigger spam filters.
It examines your content, formatting, links, and sending infrastructure to predict whether your message will reach the inbox or spam folder.
What does an email deliverability consultant do?
An email deliverability consultant helps businesses fix problems that prevent emails from reaching inboxes.
They analyze DNS records, list quality, sender reputation, bounce rates, and spam triggers while guiding proper warmup strategies.
